Modulating Butterfly Valve Control

ABSTRACT

A method and system for controlling a fluid valve are described that avoid the effects of hysteresis. In hysteresis, the power signals associated with a valve position are different on the upstroke and downstroke. As a result, predicting the valve position can be difficult if you only know the current power signal. Instead of using upstrokes and downstrokes, a valve can momentarily be set to zero power, or a rest position when receiving a new command signal. This way the command signal is applied from a zero power or rest position, making the valve position more predictable and accurate.

TECHNICAL FIELD

The present disclosure is directed to fluid valves and more particularlyto valve control systems.

BACKGROUND OF THE INVENTION

When using a butterfly valve for flow control, valve hysteresis limitsprecision, as valve position is not exclusively dependent on input.Valve position is additionally dependent on prior input and currentposition. As such, if the input signal is decreased, the hysteresiscauses a dead zone where decreasing the input signal does not decreasethe valve position until the decreasing curve is reached. As a result,for any specific input signal, there exists a range of potential valvepositions dependent on the prior peak input signal. The dead zone alsoprevents fine adjustments of valve position.

BRIEF SUMMARY OF THE INVENTION

One embodiment under the present disclosure comprises a butterfly valvefor manipulating fluid flow, comprising: a housing configured to receivea fluid; a disc configured to rotate on its axis within the housing; anda controller configured to regulate fluid flow through the butterflyvalve by rotating the disc on its axis, wherein the controller isconfigured to apply a first input signal to move the disc from a restposition to a first position, and wherein when the controller receives acommand to move the disc to a second position, if the second position isa larger rotational distance to the rest position than the firstposition, then the controller applies a second input signal associatedwith the second position, and if the second position is a smallerrotational distance to the rest position than the first position, thenthe controller first applies zero input and then applies a second inputsignal associated with the second position.

Another embodiment can comprise a valve for controlling fluid flow,comprising: a housing configured to receive a fluid; a gate operable toat least partially restrict a flow of the fluid through the housing; anda controller configured to adjust the gate, wherein the controller isconfigured to receive a first command to apply a first input signal tothe gate, the first input signal associated with moving the gate from arest position to a first position, the controller further configured toreceive a second command to apply a second input signal to the gate, thesecond input signal associated with moving the gate from the restposition to a second position, wherein if the second position is betweenthe rest position and the first position, then the controller isconfigured to adjust the gate to the rest position momentarily and thento apply the second input signal.

Another embodiment can comprise a method of controlling a fluid valve,comprising: sending a first command signal to a controller for the fluidvalve, the controller configured to adjust a gate of the fluid valve toa first position from a rest position; and sending a second commandsignal to the controller, the second command signal associated with asecond position between the first position and the rest position,wherein the controller is configured to, upon receiving the secondcommand signal, adjust the gate to the rest position momentarily andthen adjust the gate to the second position.

The foregoing has outlined rather broadly the features and technicaladvantages of the present invention in order that the detaileddescription of the invention that follows may be better understood.Additional features and advantages of the invention will be describedhereinafter which form the subject of the claims of the invention. Itshould be appreciated by those skilled in the art that the conceptionand specific embodiment disclosed may be readily utilized as a basis formodifying or designing other structures for carrying out the samepurposes of the present invention. It should also be realized by thoseskilled in the art that such equivalent constructions do not depart fromthe spirit and scope of the invention as set forth in the appendedclaims. The novel features which are believed to be characteristic ofthe invention, both as to its organization and method of operation,together with further objects and advantages will be better understoodfrom the following description when considered in connection with theaccompanying figures. It is to be expressly understood, however, thateach of the figures is provided for the purpose of illustration anddescription only and is not intended as a definition of the limits ofthe present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, reference isnow made to the following descriptions taken in conjunction with theaccompanying drawings, in which:

FIG. 1 is a diagram of hysteresis.

FIG. 2 is a diagram of one embodiment under the present disclosure.

FIG. 3 is a diagram of a butterfly valve under the present disclosure.

FIGS. 4A-4D are diagrams of a butterfly valve under the presentdisclosure.

FIG. 5 is a flow chart of a method embodiment under the presentdisclosure.

FIG. 6 is a flow chart of a method embodiment under the presentdisclosure.

FIG. 7 is a flow chart of a method embodiment under the presentdisclosure.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIG. 1 , a traditional valve control curve illustratingthe effects of hysteresis can be seen. At 1, increasing input (theupstroke 100) can move a valve to a given position, near 2. At 2, asdecreasing input begins, at first the valve position does not change,then the valve will move to a different position and begin closing withdecreasing input (the downstroke 200). The valve does not changeposition right away due to hysteresis, only proceeding to the downstrokeonce the changing signal was significant enough to overcome thehysteresis. During the downstroke 200 the valve position will follow 3.Arrow 2 shows a dead zone in which position and control of the valve isimprecise. A dead zone 4 also exists when the input signal is increasedafter the position was decreased, such as going from 3 back to 1, whichwould cause dead zone 4. As can be seen, for any given input value, twodifferent valve positions are possible. To determine valve position, onemust know whether the valve is undergoing the upstroke 100 or downstroke200 and prior signal/position. This adds uncertainty into the controlprocess for the valve.

Solutions for this problem include numerous embodiments under thepresent disclosure. One solution to the effect of hysteresis on abutterfly valve, where upstroke and downstroke have different valvelocations for the same input signal, is to try and stay on the upstroke,or always be increasing input to achieve new position. Referring to FIG.2 , a manner of controlling input signals for a valve under the presentdisclosure can be seen. An initial input 1 can take the valve positionto a given position on the upstroke 100. When a new valve position isdesired, the new position may be higher or lower on the upstroke 100. Ifhigher, then an additional input signal 2 a is applied resulting in anew position 3 a. However, sometimes the desired new position is loweron the upstroke 100. Previously, the decreasing signal would have noimpact on valve position until the signal reached the downstroke curve(see FIG. 1 , line 2) then, if the decrease was significant enough toovercome the hysteresis, the valve position would proceed down thedownstroke curve until the position on the downstroke curvecorresponding to the new input was reached. In these situations, finemovements are very difficult to measure or control, and it results inmultiple possible positions for the same input signal. Under the presentdisclosure, such as in FIG. 2 , the control system can close the valveat 2, then apply a new input signal 3, that is lower than previous inputsignal 1, resulting in a position 3 of the valve lower on the upstroke100.

FIG. 3 shows an embodiment of a butterfly valve 300. As shown, butterflyvalve 300 is between pipes 310, 312 that are transporting a fluid 315.Butterfly valve 300 comprises a disc 320 that spins on its axis on rod340. Housing 330 can be adapted to connect to pipes 310, 312 and toprovide rigidity and protection for rod 340 and disc 320. Modulator 350can couple to rod 340 such that it can spin the rod 340 and therebycontrol the opening and closing of disc 320 to block or restrict thefluid 315. Controller 360 can couple to modulator 350. In someembodiments modulator 350 and controller 360 can comprise one component.Controller 360 can be communicatively coupled to a control system 370,such as a vehicle control system, HVAC (heating, ventilation and airconditioning) control system, or another control system. Connections canbe wired or wireless. A user of control system 370, or software runningon the control system 370, can direct the opening and closing of disc320, and thereby the butterfly valve 300.

FIGS. 4A-4D show an embodiment of a butterfly valve 450 in a pipe 400with reference to some of the teachings described herein. Fluid in pipe400 can follow a direction of flow 420. At time 410 a, the valve 450 isclosed. In FIG. 4B, at time 420 a an input signal SA (not shown) hasmoved the valve 450 to position A. In FIG. 4C, at time 430 a, an inputsignal SB (not shown) has moved the valve 450 from position A toposition B (where B is greater than A, as in a greater angle fromhorizontal or closed in this view). In FIG. 4D, at time 440 a, it isdesired for the valve 450 to go to position C. Previously, for cases inwhich C is between A and B, a downstroke would add imprecision tocontrol of the valve 450 via a dead zone (caused by hysteresis).Previously, signal would be reduced to reach point C. however, due tohysteresis, this method can be imprecise. For example, moving toposition B might require 10 volts when moving from 0, and moving toposition C from 0 could require 5 volts. Due to hysteresis, when atpoint B, powering down from 10 volts to 5 volts will not necessarilyresult in the valve moving to position C. As shown in FIGS. 1 and 2 ,the input signal for a given position is different on the upstroke andthe downstroke.

The current disclosure can utilize a different system or method ingetting from B to C. Under the present disclosure, the input signal canbe set to 0 momentarily and then an input sign S_(C) (not shown) can beapplied to move the valve to position C. In this embodiment valve 450 isconstructed to be horizontal/closed at zero power. In the view shown inFIG. 4 , C can be any value below B. If C were larger than B (greaterangle from horizontal) then the system would not have to momentarily goto 0, but would just apply more power to move from B to a higherposition.

The embodiment shown in FIGS. 4A-4D comprises a valve 450 that is set tohave zero power be a closed position. However, other embodiments arepossible wherein the closed position requires power. If, for instance,the zero position requires 10 volts, then 10 volts can be taken as areference point, and power inputs to achieve various positions, such asA, B, and C in FIG. 4 , can all be measured with reference to 10 voltsat the closed position. Going to the zero position can comprise goingdown to 10 volts from whatever current voltage is at the respectiveposition. Other valves may incorporate different setups such as a valvebeing open at zero power, or at another position.

FIG. 5 shows a possible method 500 for controlling a valve under thepresent disclosure. Step 510 is sending a first command signal to acontroller comprising the valve, the controller configured to adjust agate of the fluid valve to a first position from a rest position. Step520 is sending a second command signal to the controller, the secondcommand signal associated with a second position between the firstposition and the rest position, wherein the controller is configured to,upon receiving the second command signal, adjust the gate to the restposition momentarily and then adjust the gate to the second position.

FIG. 6 shows possible method 600 of constructing a valve under thepresent disclosure. Step 610 is providing a housing. Step 620 iscoupling a gate to the housing, the gate able to at least partiallyrestrict a flow of fluid through the housing. Step 630 is coupling acontroller to the housing, the controller operable to adjust the gate,wherein the controller is configured to receive a first command to applya first input signal to the gate, the first input signal associated withmoving the gate from a rest position to a first position, the controllerfurther configured to receive a second command to apply a second inputsignal to the gate, the second input signal associated with moving thegate from the rest position to a second position, wherein if the secondposition is between the rest position and the first position, then thecontroller is configured to adjust the gate to the rest positionmomentarily and then to apply the second input signal.

FIG. 7 shows another possible method embodiment 700 for controlling abutterfly valve under the present disclosure. Step 710 is receiving, ata controller for a butterfly valve, a first command indicating a firstposition for the butterfly valve, the first position indicating an angleA measured from a rest position. Step 720 is adjusting, by thecontroller, the butterfly valve to the first position. Step 730 isreceiving, at the controller, a second command indicating a secondposition, the second position indicating an angle B measured from therest position. Step 740 is comparing, by the controller, angle A andangle B. At 750, if A is greater than B, then adjusting, by thecontroller, the butterfly valve to the rest position momentarily, andthen moving the butterfly valve to the second position. At 760, if B isgreater than A, then adjusting, by the controller, the butterfly valveto the second position. Alternatively, the controller can compare thepower levels associated with the commands, instead of an angle. At step730, a second command is received and then at 740 the power levels ofthe first and second commands are compared. If the second power level isless than the first power level from the first command, then thecontroller resets the valve to the rest position momentarily beforemoving to the second position.

Although description has focused on butterfly valves, other valves thatundergo hysteresis may utilize the teachings of the present disclosureas well. Butterfly, gate, ball, and other types of valves that undergohysteresis can take advantage of the teachings presented herein. Thisdisclosure could be applied to any valve subject to effects ofhysteresis. For example, control logic can be modified as taught hereinto mitigate/eliminate the effect of hysteresis and ensure that there isonly one achievable result (e.g. valve position) corresponding to agiven input signal. One means of achieving this is by ensuring that thevalve is always operating on the upstroke curve (alternatively, onecould ensure always on the downstroke curve). In order to operateexclusively on a single curve, all changes in input signal that move thevalve to a new position can be in a common known direction (be thatincreasing or decreasing). When the input delta is not in that specifieddirection—then the valve can be returned to a known or reset condition(signal/position combination). This can be a condition where theupstroke and downstroke curves are coincident such as full close or fullopen—as appropriate such that the signal change from that known restposition to the new position will be in the intended direction andaccordingly valve operated on the specified curve. Valves under thecurrent disclosure can comprise plastic, metal, composites, or any otherappropriate material or mixture of materials. Some components of a valvemay be one material, while other components may comprise other types ofmaterials.

Some embodiments under the present disclosure include momentarilyapplying zero power. “Momentarily” will typically be a time period lessthan a second. But any short time interval can be used if itaccomplishes the desires of the user and provided the interval does notunacceptably impact the performance of the system in which the valve isutilized.

The embodiments described above utilize a momentary application of zeropower to reset a gate/ball in a valve to a closed position. Additionalembodiments under the current disclosure can use a reversed design witha reset or rest position at full power—instead of returning to the zeroinput it would return to 100% input. This could be used in valves thatare normally open and powered to close. In these embodiments, the“reset” position can still be a closed position, but it is done bysending 100% input. A further embodiment can comprise having a resetposition at an open valve with 100% power. This can be useful insituations where it is preferred to have the valve fully opened. Forthese embodiments 100% input can be provided to open the valve at eachreset instead of closing it.

In embodiments where 100% input is used at the reset position, thenpower can be subtracted or lowered in a predictable way. The behavior ofthe valve would essentially be descending the graph of FIG. 1 , alongcurve 3. As the valve descends curve 3, and descends in power, theposition of the valve will remain predictable. When the valve mustascend curve 3 to a higher value, then applying full power will returnthe gate position to the top of curve 3, and then power can besubtracted in a predictable way to move to the new desired position.

Although the present invention and its advantages have been described indetail, it should be understood that various changes, substitutions andalterations can be made herein without departing from the spirit andscope of the invention as defined by the appended claims. Moreover, thescope of the present application is not intended to be limited to theparticular embodiments of the process, machine, manufacture, compositionof matter, means, methods and steps described in the specification. Asone of ordinary skill in the art will readily appreciate from thedisclosure of the present invention, processes, machines, manufacture,compositions of matter, means, methods, or steps, presently existing orlater to be developed that perform substantially the same function orachieve substantially the same result as the corresponding embodimentsdescribed herein may be utilized according to the present invention.Accordingly, the appended claims are intended to include within theirscope such processes, machines, manufacture, compositions of matter,means, methods, or steps.

What is claimed is:
 1. A butterfly valve for manipulating fluid flow,comprising: a housing configured to receive a fluid; a disc configuredto rotate on its axis within the housing; and a controller configured toregulate fluid flow through the butterfly valve by rotating the disc onits axis, wherein the controller is configured to apply a first inputsignal to move the disc from a rest position to a first position, andwherein when the controller receives a command to move the disc to asecond position, if the second position is a larger rotational distanceto the rest position than the first position, then the controllerapplies a second input signal associated with the second position, andif the second position is a smaller rotational distance to the restposition than the first position, then the controller momentarilyapplies zero input and then applies a second input signal associatedwith the second position.
 2. The butterfly valve of claim 1 wherein therest position comprises a closed position.
 3. The butterfly valve ofclaim 1 wherein the rest position comprises an open position.
 4. Thebutterfly valve of claim 1 wherein the controller comprises a computerremote to the disc.
 5. The butterfly valve of claim 1 wherein thecontroller is communicatively coupled to a remote computer.
 6. Thebutterfly valve of claim 1 wherein the controller is communicativelycoupled to a vehicle control system.
 7. The butterfly valve of claim 1wherein the butterfly valve is operable to regulate a flow of air in ahelicopter.
 8. The butterfly valve of claim 1 wherein the controller iscommunicatively coupled to a control system for an aircraft.
 9. A valvefor controlling fluid flow, comprising: a housing configured to receivea fluid; a barrier operable to at least partially restrict a flow of thefluid through the housing; and a controller configured to adjust thebarrier, wherein the controller is configured to receive a first commandto apply a first input signal to the barrier, the first input signalassociated with moving the barrier from a rest position to a firstposition, the controller further configured to receive a second commandto apply a second input signal to the barrier, the second input signalassociated with moving the barrier from the rest position to a secondposition, wherein if the second position is between the rest positionand the first position, then the controller is configured to adjust thebarrier to the rest position momentarily and then to apply the secondinput signal.
 10. The valve of claim 9 wherein the valve comprises agate valve and the barrier comprises a gate.
 11. The valve of claim 9wherein the housing comprises a plastic.
 12. The valve of claim 9wherein the valve comprises an air flow system in an aircraft.
 13. Thevalve of claim 9 wherein the controller is communicatively coupled to acontrol system of an aircraft.
 14. The valve of claim 9 wherein thecontroller is communicatively coupled to an HVAC control system.
 15. Thevalve of claim 9 wherein the controller is coupled to the gate by anactuator.
 16. The valve of claim 9 wherein the rest position isassociated with an input signal of
 0. 17. A method of controlling afluid valve, comprising: sending a first command signal to a controllerfor the fluid valve, the controller configured to adjust a barrier ofthe fluid valve to a first position from a rest position; and sending asecond command signal to the controller, the second command signalassociated with a second position between the first position and therest position, wherein the controller is configured to, upon receivingthe second command signal, adjust the barrier to the rest positionmomentarily and then adjust the barrier to the second position.
 18. Themethod of claim 17, wherein the rest position is an open position. 19.The method of claim 17, wherein the rest position is a closed position.20. The method of claim 17, wherein the fluid valve comprises a ballvalve.